The present invention is a process for the disproportionation of cycloorganosilanes using sodium borohydride as a catalyst. The process requires the presence of a hydrogen and a cycloorgano-substituent bonded to a single silicon atom, where the cycloorgano-substituent is a radical selected from a group consisting of aryls, substituted aryls, cycloalkyls, and substituted cycloalkyls.
The use of a catalyst to effect the disproportionation of arylsilanes is known. For Example, Wagner, U.S. Pat. No. 2,746,981, issued May 22, 1956, teaches the preparation of diaryldichlorosilanes by heating monoaryldichlorosilanes in the presence of a Friedel-Crafts type catalyst taken from the group consisting of aluminum or boron chloride.
Japanese Patent No. 263189, published in 1987, teaches a process where arylboranes for example triphenylborane, is used to catalyze the disproportionation of aryldihalosilanes under conditions of reduced pressure. Running the process at reduced pressure is reported to increase the yield of diarylhalosilane.
The present process describes the use of sodium borohydride as a catalyst for the disproportionation of cycloorganosilanes. The sodium borohydride is essentially insoluble in the process, making it especially useful as a fixed-bed in a continuous process. Cycloorganosilanes prepared by the present process are useful, for example, for the preparation of siloxane polymers and for the preparation of release coatings for paper.